The winding process is much faster than the spinning process and therefore a small number of winding stations is able to wind or rewind the yarn produced in a much higher number of spinning stations. This results in the production of a large number of wound yarn packages which are then combined into a smaller number of larger-size bobbins which represent the final product of the spinning-winding machine. For the winding stage the packages produced in the spinning station must be presented to the winding stations with a yarn end in a predetermined position, this being generally a vertical position with the yarn end inserted through the upper aperture of the tube which forms the core of the package.
The winding machine is thus able to automatically grasp the yarn end and commence its rewinding to form the bobbin.
Currently available spinning-winding machines are characterised by a large number of spinning stations of up to one thousand or more, but only a small number of winding stations of the order of some tens, between which the empty tubes recycled from the winding machine for receiving the new wound packages and the yarn-wound packages to be rewound are conveyed. In order to reduce the work load this conveying together with the prearranging of the packages is handled in recently designed spinning-winding machines by automatic conveyor devices of various designs which limit the work of the operators to mere supervision and intervention in the case of possible machine malfunction.
The winding stage generally has a higher capacity than the spinning stage to allow the winding machine to handle the yarn production without any build-up during its operation. The problem of conveying the packages and tubes was dealt with up to a few years ago by interposing truck-mounted bins between the two stages to randomly receive the full packages or empty tubes, and from which they were withdrawn by loading and arranging devices or more simply by the operators themselves.
The winding machine discharges not only tubes completely empty of yarn for recycling to the spinning machine, but also a small but not negligible number of tubes not completely empty of yarn, from which the automatic winding machine is unable to take up further yarn because the end is no longer recoverable by the devices with which each station is equipped.
These irregular packages from which part of the yarn cannot be unwound arise because of imperfect package winding during the spinning operation, resulting in successive yarn turns becoming engaged under slack turns which have been previously wound. So that when these turns are unwound in the winding machine they become blocked with the result that the yarn breaks at a point prior to the path through which the yarn is under the control of the winding members, and along which yarn continuity can be automatically restored by splicing.
These tubes have to be selected, recovered and fed to the package arranging device in order to use up the yarn still wound on them by finding its end and then refeeding them to the winding machine.
The known art comprises a large number of spinning-winding machine arrangements.
According to German patent No. 3235442 of Murata Kikai, the packages and tubes are conveyed between the spinning and winding machines with the aid of disc supports provided with a tube engagement peg, the discs being placed on conveyor belts.
U.S. Pat. No. 3,941,323 of Savio describes a device for preparing wound packages for rewinding, including searching for, preparing and retaining the yarn end. U.S. Pat. No. 4,432,198 of the same proprietor describes a device for conveying packages between the two stages.
U.S. Pat. No. 4,571,931 of Schlafhorst describes a transfer device between the spinning and winding machines which acts as a buffer store between the two machines and feeds the packages to the winding machine when requested by the winding stations. This device also allows for prearranging of the packages. The proposed methods include a large variety of conveyor systems, namely smooth conveyor belts on which the packages are either laid on their sides or supported by said discs, conveyor belts provided with fixed vertical pegs for engaging the tubes and packages in a vertical position, sector elevators and conveyors, and gripper devices, generally combined with each other.